1. Field of the Invention
The present invention pertains to piezoelectric diaphragms, and particularly to a piezoelectric diaphragm assembly with stacked diaphragms and/or a pump incorporating the same.
2. Related Art and Other Considerations
A piezoelectric material is permanently-polarized and will produce an electric field when the material changes dimensions as a result of an imposed mechanical force. This phenomenon is known as the piezoelectric effect.
Layers of piezoelectric material can be stacked to form a multiple layer piezoelectric device. For example, U.S. Pat. No. 6,215,228 to Yamazaki discloses stacking multiple piezoelectric layers and multiple internal electrodes. U.S. Pat. No. 5,245,734 to Issartel discloses stacking and pressing alternating layers of piezoceramic material and interdigital electrode material. Issartel also discloses boundary discontinuities within the electrode structure which form areas in which electrode edges do not make contact with the common electrical collectors of the piezoactuators and in which the piezoceramic layers are prevented from touching one another.
Examples of piezoelectric diaphragms and pumps incorporating the same are described and shown in PCT Patent Application PCT/US01/28947, filed Sep. 14, 2001; U.S. patent application Ser. No. 10/380,547, filed May 28, 2003, entitled “Piezoelectric Actuator and Pump Using Same”; U.S. patent application Ser. No. 10/388,589, filed Mar. 17, 2003, entitled “Piezoelectric Actuator and Pump Using Same”, and U.S. Provisional Patent Application 60/670,692, filed Apr. 13, 2005, entitled “PIEZOELECTRIC DIAPHRAGM ASSEMBLY WITH CONDUCTORS ON FLEXIBLE FILM”, all of which are incorporated herein by reference.
One challenge in piezoelectric diaphragm technology is to obtain not only responsiveness to an applied electrical signal, but also a sufficient force as exerted through the piezoelectric diaphragm for acting upon a medium such as a fluid, for example. What is needed, therefore, and an object of the technology disclosed herein, is a piezoelectric diaphragm assembly which provides enhanced force.